Delta MegaLine 4889 Pressurized Ball Point Refill. The Delta Megaline system allows not only writing upside down or under the most extreme environmental condition, but also a writing with the highest speeds. The air tight system gives these refills a literally unlimited shelf-life. They are equipped with a stainless steel tip manufactured with the upmost precision as well as special ink pastes developed exclusively for Delta MegalLine pressurized refills.